Nanoscale Electron Transport through WO ₃ and H x WO ₃

Tungsten trioxide (WO 3 ) is a cornerstone material for emerging oxide nanoelectronics, yet its transport behavior at the ultimate scaling limits remains poorly understood. In this work, we employ first-principles quantum transport simulations, combining density functional theory (DFT) with the nonequilibrium Green’s function (NEGF) formalism, to investigate the electronic properties of H x WO 3 junctions in the sub-5 nm regime. We identify a critical structural scaling threshold of six molecular layers (∼26.9 Å), below which quantum tunneling dominates, and above which stable semiconducting behavior and effective conductance modulation emerge. Using this 6-layer framework, we demonstrate that hydrogen intercalation WO 3 in induces a monotonic enhancement in current density, providing a 2.5-fold increase in conductance through the filling of tungsten 5d states. Furthermore, our analysis reveals that nanoscale transport is highly sensitive to the spatial configuration of protons; specifically, OH O defects at bridging oxygen sites induce significant structural distortions (∼178° to 163°) that attenuate current by reducing orbital overlap. These results establish the fundamental scaling limits for WO 3 integration and provide a microscopic origin for the structural sensitivity of protonic transport, offering a predictive framework for the design of high-density neuromorphic and gas-sensing architectures.